Volvo 850 2.5 power loss mystery

Hi
My 1994 Volvo 850 2.5 (140hp) lost power 7 days ago, approx 1 mile after
starting from cold. It did not respond to the throttle and slowed from 60mph
to about 30mph, over a period of 15 seconds, then recovered and has been OK
ever since, during which time I have covered about 250 miles.
I took the car into the Volvo agent, who said that there no error codes
showing up, and who told me that it could have been either be the fuel pump
or the coil, neither of which show up as a fault codes. Short of replacing
both these items (the car has 205,000 miles on the clock), is there anything
I can do apart from wait for this to happen again one day?

Many thanks

John Morris

 

Did you happen to notice a kind of "hissing" sound when you lost power?
Sometimes the catalytic converter starts to break up on the inside and
pieces of metal block the flow of exhaust. This can be an intermittent
problem for a time until enough of it breaks apart and plugs it up for good.
Just another possibility.

 

Was it misfiring or spluttering or giving any other such symptoms during the
power loss? You;ll have to give alittle more detail for us to stand a chance
at surmissing the problem!

Were you particularly low on fuel, any warning lamps come on, did the tacho
behave strangely etc etc?????

Tim..

 

Further details are limited, I'm afraid. There were no strange noises, no
warning lamps and the tacho reflected the revs correctly. The engine didn't
misfire or stutter, it was just that for 15 seconds or so it was as if I had
switched off the ignition (which I hadn't). I had refueled (with BP) 10
hours earlier in the day, but had only driven 3 miles since filling up. The
previous day had been one of torrential rain, with puddles that I had driven
through without problems, and this day had been dry, and windy.

Thanks again
John Morris

************

 

Right.

Well your symptoms rule out both a faulty ignition barrel (common) and ECU
power failure, and LT ignition switching- becuase the tacho remained
indicating correct engine revs, but you were just coasting.

Therefore that does leave fuel pump and relay, and secondary igintion (this
includes the amp, and coil). Both would be able to kill the engine dead
wihtout any spluttering or partial power loss.

I'd check the connections at the coil pack, and the fuel pump fuse, and
possibly get your hands on a new fuel pump relay (underneath the fuse box
lid- 2 screws to remove) just incase it does it again.

If you are handy with a soldering iron, you can open up your exisiting relay
and resolder all the joints instead.

Tim..

 

Thanks for the advice, I'll certainly try to get hold of a fuel pump relay,
and will get the garage to check out the other items.
John

 

Is this a 10 or 20valver?

Former is Single ECU Fenix and latter is dual ECU LH3.2 / EZ.

Tim..